Disturbed flow in the juxta-anastomotic area of an arteriovenous fistula correlates with endothelial loss, acute thrombus formation and neointimal hyperplasia

BACKGROUND

Clinical failure of arteriovenous fistulae (AVF) is frequently due to juxta-anastomotic neointimal hyperplasia (JANIH). Although the mouse AVF model recapitulates human AVF maturation, previous studies focused on the outflow vein distal to the anastomosis. We hypothesized that the juxta-anastomotic area (JAA) has increased NIH compared to the outflow vein.

METHOD

AVF were created in C57BL/6 mice without or with chronic kidney disease (CKD). Temporal and spatial changes of the JAA were examined using histology and immunofluorescence. Computational techniques were used to model the AVF. RNA-seq and bioinformatic analyses were performed to compare the JAA with the outflow vein. The jugular vein to carotid artery AVF model was created in Wistar rats.

RESULT

The neointima in the JAA shows increased volume compared to the outflow vein. Computational modeling shows increased volume of disturbed flow at the JAA compared to the outflow vein. Endothelial cells are immediately lost from the wall contralateral to the fistula exit, followed by thrombus formation and JANIH. Gene Ontology (GO) enrichment analysis of the 1862 differentially expressed genes (DEG) between the JANIH and the outflow vein identified 525 overexpressed genes. The rat jugular vein to carotid artery AVF showed changes similar to the mouse AVF.

CONCLUSION

Disturbed flow through the JAA correlates with rapid endothelial cell loss, thrombus formation, and JANIH; late endothelialization of the JAA channel correlates with late AVF patency. Early thrombus formation in the JAA may influence later development of JANIH.

IDEAL Phase 2a Results: Posterior Rectus Sheath Flap for Hiatal Augmentation in Complex Paraesophageal Hernias

OBJECTIVE

To report the developmental phase results of posterior rectus sheath hiatal flap augmentation (PoRSHA), a promising surgical innovation for large and recurrent paraesophageal hernias.

BACKGROUND

Durable hernia repair for large paraesophageal hernias continues to be a surgical challenge. PoRSHA addresses the challenges of current and historical approaches to complex paraesophageal hernias and demonstrates significant promise as a successful alternative approach.

METHODS

Using the IDEAL framework, we outline the technical modifications made over the first 27 consecutive cases using PoRSHA. Outcomes measured included hernia recurrence on routine imaging at 6 months and 2 years, development of a postoperative abdominal wall eventration and incidence of solid food dysphagia.

RESULTS

Twenty-seven patients at our single institution with type III (n=12), type IV (n=7) or recurrent (n=8) paraesophageal hernias underwent PoRSHA. Surgery was safely and successfully carried out in all cases. Stability of the technique was reached after 16 cases resulting in four main repair types. At an average follow up of 11 months, we observed no radiologic recurrences, no abdominal eventrations or hernias at the donor site and one patient with occasional solid food dysphagia that resolved with dilation.

CONCLUSIONS

PoRSHA can not only be safely added to conventional hiatal hernia repair with appropriate training, but also demonstrates excellent short-term outcome. While the long-term durability with 5 year follow up is still needed, here we provide cautious optimism that PoRSHA may represent a novel solution to the longstanding high recurrence rates observed with current complex PEH repair.

Octogenarians undergoing pancreaticoduodenectomy: Assessing outcomes, disposition, and timing of chemotherapy

BACKGROUND

Inclusion of pancreaticoduodenectomy has demonstrated higher rates of curative treatment in pancreatic cancer, yet prior research has suggested increased postoperative complications in octogenarians (patients older than 80 years). This study aimed to understand the impact of age on patients undergoing a pancreaticoduodenectomy, focusing on postoperative outcomes and return to intended oncologic treatment.

MATERIALS AND METHODS

We conducted a single-institution retrospective cohort study for patients undergoing pancreaticoduodenectomy from 2007 to 2018. Collected data included demographics, preoperative comorbidities, and postoperative data (length of stay, 30-day mortality, 1-year mortality, infection, discharge location). Data were separated into 2 cohorts: octogenarians (≥ 80 years) and nonoctogenarians (< 80). χ2 and independent-sample t tests were used for analysis.

RESULTS

A total of 649 patients underwent pancreaticoduodenectomy from 2007 to 2018; 63 (9.7%) were octogenarians. No differences were found in infectious complications (P = .607), 30-day mortality (P = .363), or 1-year mortality (P = .895). Octogenarians had a longer length of stay (P = .003) and were more likely to be discharged to skilled nursing facilities (P < .001). There was no significant difference in neoadjuvant chemotherapy administration, although octogenarians were less likely to receive adjuvant chemotherapy (P = .048) and declined adjuvant therapy at a higher rate (P = .003).

CONCLUSION

Performing a pancreaticoduodenectomy in octogenarians can be safe and effective in a properly selected cohort. Although postoperative morbidity and mortality are similar to younger patients, elderly patients are more likely to be discharged to nursing facilities and less likely to receive adjuvant chemotherapy. This study suggests that age alone should not be a discriminating factor when discussing surgical therapy for pancreatic cancer treatment in octogenarians.

Pancreatic neuroendocrine tumors: Surgical outcomes and survival analysis

BACKGROUND

Pancreatic neuroendocrine tumors are rare, with rising incidence and limited clinicopathological studies.

METHODS

Adult patients with pNET at a single tertiary care center were retrospectively evaluated.

RESULTS

In total, 87 patients with histologically confirmed pNET who underwent resection were evaluated. 11% of patients had functioning pNETs: 9 insulinoma and 1 VIPoma. The majority (88.5%) were nonfunctioning. The most common surgical procedure performed was distal pancreatectomy with splenectomy (36.8%). 35.6% of cases were performed with minimally invasive surgery (MIS). MIS patients had fewer postoperative complications, shorter length of stay, and fewer ICU admissions.Disease-free survival (DFS) was unaffected by tumor size (p = 0.5) or lymph node status (p = 0.62). Patients with high-grade (G3) tumors experienced significantly shorter DFS (p = 0.02).

CONCLUSIONS

This series demonstrates that survival in patients with pNET is driven mostly by tumor grade, though overall most have long-term survival after surgical resection. Additionally, an MIS approach is efficacious in appropriately selected cases.

Diagnostic Colour Duplex Ultrasound for Type IIIb Endoleak

Introduction

This report presents the treatment of an aortic endovascular aneurysm repair (EVAR) device failure, focusing on the use of colour duplex ultrasound (CDUS) to diagnose and confirm effective treatment of a type IIIb endoleak.

Report

An 89 year old man with a history of EVAR was transferred to the authors’ centre with complaints of abdominal pain and a pressure sensation behind the umbilicus. A previously stable 11 cm aneurysm sac was visualised on computed tomography angiography in addition to a newly suspected type IIIb endoleak, which was confirmed via CDUS. He underwent successful endovascular repair with a stent across the limb defect. The patient was discharged uneventfully and was followed for surveillance.

Discussion

Type IIIb endoleak is an underreported complication after EVAR. CDUS of type IIIb endoleak aided in localisation and characterisation of the graft failure, and confirmed successful endovascular treatment of the endoleak defect in the side limb. Locating the point of graft failure using CDUS preceding endovascular repair of type IIIb endoleaks guides interventions and repair outcomes. It is a rare opportunity to report a case of acute type IIIb endoleak with CDUS that definitively localised an endograft defect.

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Safe, economic, and effective surveillance is imperative after EVAR.

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Colour duplex ultrasound should be considered in the preoperative period to characterise the endoleak.

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Colour duplex ultrasound can quantify flow velocity and direction in the setting of endoleak.

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Colour duplex ultrasound may be used to confirm appropriate treatment of endoleak.

Primary cilia expression in bone marrow in response to mechanical stimulation in explant bioreactor culture

Bone marrow contains a multitude of mechanically sensitive cells that may participate in mechanotransduction. Primary cilia are sensory organelles expressed on mesenchymal stem cells (MSCs), osteoblasts, osteocytes, and other cell types that sense fluid flow in monolayer culture. In marrow, cilia could similarly facilitate the sensation of relative motion between adjacent cells or interstitial fluid. The goal of this study was to determine the response of cilia to mechanical stimulation of the marrow. Bioreactors were used to supply trabecular bone explants with low magnitude mechanical stimulation (LMMS) of 0.3 ×g at 30 Hz for 1 h/d, 5 d/week, inducing shear stresses in the marrow. Four groups were studied: unstimulated (UNSTIM), stimulated (LMMS), and with and without chloral hydrate (UNSTIM+CH and LMMS+CH, respectively), which was used to disrupt cilia. After 19 days of culture, immunohistochemistry for acetylated α-tubulin revealed that more cells expressed cilia in culture compared to in vivo controls. Stimulation decreased the number of cells expressing cilia in untreated explants, but not in CH-treated explants. MSCs represented a greater fraction of marrow cells in the untreated explants than CH-treated explants. MSCs harvested from the stimulated groups were more proliferative than in the unstimulated explants, but this effect was absent from CH treated explants. In contrast to the marrow, neither LMMS nor CH treatment affected bone formation as measured by mineralising surface. Computational models indicated that LMMS does not induce bone strain, and the reported effects were thus attributed to shear stress in the marrow. From a clinical perspective, genetic or pharmaceutical alterations of cilia expression may affect marrow health and function.